Astronomers detect first atmosphere on habitable-zone rocky planet LHS 1…
Researchers have identified a helium-rich atmosphere on LHS 1140b, the first rocky planet in a habitable zone found to retain such a layer. This breakthrough suggests rocky worlds can survive the radiation of red dwarf stars.
Astronomers have confirmed the existence of an atmosphere surrounding LHS 1140b, a rocky, Earth-like planet located approximately 48 light-years from Earth in the constellation Cetus. This discovery, detailed in a study published in Science on July 16, 2026, marks the first time an atmosphere has been identified on a rocky exoplanet orbiting within its host star's habitable zone.
LHS 1140b and the search for habitable environments
LHS 1140b orbits a red dwarf star that is significantly smaller and cooler than the Sun. While the planet was discovered in 2017, its status as a candidate for habitability has been refined by recent data. It sits within the "Goldilocks zone," the orbital region where temperatures are considered sufficient to allow for liquid water on a planetary surface. The planet is estimated to be 5.6 times the mass of Earth with a radius roughly 70% larger. Astronomers note that it is likely tidally locked, meaning one side of the planet permanently faces its host star.
The research team, led by Collin Cherubim of Harvard University, utilized the Warm Infrared Echelle (WINERED) Spectrograph on the Magellan Clay telescope at the Las Campanas Observatory in Chile. By observing the planet as it transited in front of its star, researchers detected signatures of escaping helium. Cherubim developed a computer model during his doctoral work that predicted the existence of such helium-dominated atmospheres on rocky worlds, providing the framework for the observations.
The detection of helium escaping into space suggests that the planet has retained an atmosphere for billions of years, despite the high-energy radiation often emitted by red dwarf stars. Previous research has frequently questioned whether rocky planets orbiting M-class dwarf stars could maintain an atmospheric envelope against stellar winds and ultraviolet radiation. "This is a bona fide, robust way of saying yes, atmospheres can survive on rocky exoplanets," Cherubim stated.
Scientific implications and future study
While the presence of helium is confirmed in the upper atmosphere, researchers emphasize that the finding does not equate to the discovery of life. Helium alone is not conducive to sustaining biological organisms as we know them. However, the study suggests that the helium layer may overlie other gases closer to the surface, such as water vapor, carbon monoxide, carbon dioxide, or oxygen, though these have not been definitively observed. Robin Wordsworth, a professor at Harvard and one of the study's advisors, noted, "Twenty years ago we wondered whether other terrestrial-type planets even existed. Then we learned they’re common, and found some in the habitable zone. The next question was whether any of them had managed to keep an atmosphere. Now we know at least one has."
The researchers also observed a second planet in the same system, LHS 1140c, but reported no evidence of an atmosphere. Future investigations are expected to focus on characterizing the full composition of the atmosphere on LHS 1140b to better understand the planet’s potential for hosting liquid water. Scientists maintain that while LHS 1140b remains a significant subject of study, other candidates such as K2-18b and the TRAPPIST-1 system continue to be scrutinized for signs of habitability.
